PARIS — The French have been ideally positioned to take advantage of the growing rift in recent weeks between the Arab monarchies of the Persian Gulf and the United States. Representatives of those monarchies met with President Obama on Wednesday to discuss their differences and especially their worries over a proposed nuclear deal with Iran.

Just days ago, France’s foreign minister, Laurent Fabius, said that French officials were working on memorandums of understanding for “several tens of billions of euros” in projects in Saudi Arabia. Last week, President François Hollande was warmly welcomed at a meeting of the Gulf Cooperation Council, where he oversaw the signing of a $7 billion deal to sell fighter jets to Qatar.

The gulf states are irate over Mr. Obama’s determination to reach a nuclear deal with Iran, a Shiite country and regional rival that would be strengthened by the end of sanctions. Under the deal, sanctions would be lifted in exchange for Iran’s agreement to greatly slow its nuclear program. By loudly voicing doubts about the pact, analysts say, France has made itself an advocate of gulf nations while drumming up business for its own arms industry.

“By appearing slightly tougher than the rest of the Western coalition on the nuclear deal, the French find a niche for themselves, a window of opportunity,” said Dominique Moïsi, a political scientist specializing in international affairs and a founder of the French Institute of International Relations. “And by buying French, the Saudis are also showing their displeasure with the Americans.”

France’s credibility among Sunni Arab states was also enhanced by French leaders’ hard talk against the Syrian president, Bashar al-Assad, after he used chemical weapons on rebellious communities in 2013. Iran has heavily supported the government of Mr. Assad, whose Alawite sect is an offshoot of Shiism, in his civil war with mostly Sunni rebels backed by gulf nations.

Mr. Obama, by contrast, earned the gulf nations’ ire by not striking at Mr. Assad, despite having declared chemical weapons use a “red line” that would prompt American action. The British put the question of participation in strikes against the Assad government to a vote in Parliament, where it was rejected.

France, Saudi Arabia and other gulf countries have longstanding ties. During the Iran-Iraq war in the 1980s, France supported Saddam Hussein, Iraq’s Sunni leader, who was also backed by the Saudis. France vehemently opposed the United States’ invasion of Iraq in 2003, and more recently, Nicolas Sarkozy, the former French president, courted the gulf state of Qatar and made it a favored business partner, holding conferences there and forging business alliances.

Qatar has made several high-profile purchases in France, including the iconic Printemps department stores and the Paris Saint-Germain soccer club, and France sealed a lucrative deal to sell the country as many as 24 Rafale fighter jets. The United Arab Emirates has also invested in French military technology.

Mr. Hollande, sometimes called François of Arabia, has endeavored to forge strong relations with the gulf and reinforce ties with Saudi Arabia, which has a new, 79-year-old king, Salman. Gulf leaders have obliged.

“As the relationship with the United States cools, the gulf states are sending signals to the U.S. and to their own publics that they have other strategic partnerships, and France is increasingly seen as a welcome addition to the gulf security architecture,” said Emile Hokayem, a Persian Gulf-based analyst with the International Institute for Strategic Studies.

Despite the flurry of deals, France’s ability to turn a momentary advantage into a long-term asset may be limited. Notwithstanding its tough talk, France will almost certainly sign nearly any nuclear deal with Iran. And for all the bravado in gulf nations about diversifying alliances, the United States has long sold more arms than the French in the gulf and Saudi Arabia and is deeply entwined itself with Sunni Arab militaries.

In 2014, France sold about $175 million in conventional arms to the Saudis, while the United States sold about $1.2 billion, according to an archive of conventional arms sales compiled by the Stockholm International Peace Research Institute. That same year, France sold $122 million of those arms to the United Arab Emirates while the United States sold $551 million.

French domestic politics do not unambivalently support close ties with the gulf nations and Saudi Arabia, which are home to conservative forms of Islam that many French citizens oppose.

While it is unlikely to displace the United States as the gulf’s preferred superpower, France has become more active as a military player in a fraught region.

“France is in part replacing the United Kingdom as the deputy sheriff when it comes to intervention,” Mr. Moïsi said. “This is related to the sharp reduction in defense spending decided by 10 Downing Street.”

As the Americans have pushed ahead with the Iran deal, the six-country Gulf Cooperation Council has deliberately amplified the French role to express its frustration with the United States and to improve its own image, somewhat battered by the bombing campaign in Yemen and charges that some of its member countries have supported extremist Sunni groups in Syria and Iraq. So gulf leaders invited Mr. Hollande to Riyadh, Saudi Arabia, last week, making him the first Western head of state to attend one of the group’s meetings.

“Don’t underestimate the domestic value to these countries of having a French president not only on their soil but having him attend a G.C.C. meeting,” said Jonathan Eyal, the head of the Royal United Services Institute in London. “That was the first time a Western leader was there, and for them, that’s a way of signaling ‘Some Western countries may not like us, but others do.’ It deflects criticism.”

At the same time, Mr. Eyal and other experts note, neither Saudi Arabia nor Qatar is under any illusions that France can substitute for the United States.

“They know very well that the French are not going to stand in for the U.S.,” said François Heisbourg, a special adviser at the Foundation for Strategic Research in Paris. “We don’t have the weight politically, economically or strategically.”

Mr. Heisbourg added, “The point they are making is, ‘We need all the help we can get as a counterweight to Iran and a security blanket for ourselves.’ ”

And France, with its strapped economy, is only too happy to sell French goods to the gulf.

During a visit to Riyadh last week, however, Mr. Fabius, the French foreign minister, said there was a newfound sense of urgency on the part of the Saudis to “move quickly” to solidify deals with Paris, and that there would soon be memorandums of understanding between the two countries on a variety of deals, including of technologies in the health, solar and transportation industries — and potentially in nuclear energy.

Still, America’s military presence in the Persian Gulf, its economic power and the reality that Saudi Arabia and Qatar have heavily invested in American-made aircraft and weapons cast a long shadow.

“These guys are not fools, they like to have diversified portfolios,” Mr. Heisbourg said. “But they know that the biggest item in their portfolios is the United States.”

A version of this article appears in print on , Section A, Page 6 of the New York edition with the headline: Breach Between Arab Nations and U.S. Opens Opportunities for France. Order Reprints | Today’s Paper | Subscribe